Leader Power Supply 735-10D Service Manual

[bostonman]

I have a Leader Power Supply 735-10D and it has an odd problem. I found the manual (https://www.massetrecovery.com/Pictures7/leader7185d.pdf) but not any schematics, but it doesn't provide schematics.

I'm assuming the schematics don't exist, so maybe someone has had experience repairing a similar issue in the same or another power supply; or has an idea where to start looking.

It seems when I first turn it on, the display is about 1.5V less than the measured output (i.e. at 10V output the display will read 8.5V). Eventually the display is correct and matches the output voltage. This is either because I turn the dial and exercise the relay(s) or something heats in the display circuit. It's hard to tell because if I turn the knob, I need to measure the voltage and I'm uncertain if turning the knob caused the display to change or the display changed while I turned the knob. If I let it sit, it doesn't seem to change, but it always seems to just being working correctly at some point while I'm tinkering with wires to connect to something.

This isn't a big problem as I usually always measure the output voltage regardless, but would like to fix it.

Has anyone had a power supply that did this and what was the problem?

Since the voltage doesn't seem to decrease by 1.5V and the display jumps to 1.5V, this tells me the problem is within the display circuit that measures the voltage. If I turn it off for some amount of time, the display returns to being low which tells me the display is the portion that is acting up. Also, I'm uncertain if the display is 1.5V less across all voltages. As I mentioned, the more I tinker with it, the quicker it seems to begin working correctly so I somewhat haven't narrowed it down to figuring out which happens first.